Sulfated zirconia catalysts having a sulfate group supported on zirconium oxide are popular as solid acid catalysts because of their high level of activity. Recently a sulfated tin oxide catalyst having a sulfate group supported on tin oxide has been reported to be more active than sulfated zirconia catalysts (H. Matsuhashi et al, Chem. Mater. 2001 Vol. 13, pp. 3038-3042).